Onsite Wastewater Treatment Systems (OWTS) / Septic Systems


Kelsey C. Cody, Ph.D.,
Groundwater Permitting Unit Supervisor,
(707) 576-2347,

Roy O’Connor,
Engineering Geologist,
(707) 576-2670,

Rachel Prat,
Environmental Scientist,
(707) 576-2542,

Mike Reese,
Water Resources Control Engineer
(707) 576-2838,

Onsite wastewater treatment systems (OWTS) commonly known as septic systems that primarily treat domestic wastewater and employ subsurface disposal. On June 19, 2012, the State Water Resources Control Board (State Water Board) adopted Resolution No. 2012-0032, adopting the Water Quality Control Policy for Siting, Design, Operation, and Maintenance of Onsite Wastewater Treatment Systems (OWTS Policy).  This Policy uses a risk-based, tiered approach for the regulation and management of OWTS installations and replacements and sets the level of performance and protection expected from OWTS. Most notably the Policy establishes a framework that promotes Local Agency Management Plans (LAMPs) developed for local governments to implement (Active LAMPS can be found via the links in the table at the bottom of this page). The revision of Chapter 4 of the Basin Plan to incorporate the statewide OWTS Policy, with modification, has been approved by Office of Administrative Law and is now in effect. 

OWTS Policy

Russian River Pathogen Total Maximum Daily Load (TMDL)

The Adopted TMDL Action Plan includes special provisions that apply to Onsite Wastewater Treatment Systems (OWTS) within the Advanced Protection Management Program (APMP) boundary. A map outlining the APMP boundary can be found below. The map includes all parcels within the APMP boundary, whether they are developed, undeveloped, sewered, or unsewered. The APMP Boundary Parcel List is an Excel spreadsheet that is presented in portable document format (pdf). It is generated using tax assessor data for Mendocino County and Sonoma County and results in a list of Assessor Parcel Numbers (APN) and the associated addresses. You can search the pdf using the Adobe Acrobat search (or find—Ctrl F) tool. You will need either the APN for the property of interest or the site address. Sonoma County APNs are represented as 9 digit numbers with 2 dashes. Site addresses do NOT include a period following abbreviations for road, street, boulevard, or avenue. Keep your search as simple as possible; for example, if searching for the street address 5550 Skylane Boulevard, Santa Rosa, try typing in “5550 Skylane”. Parcels found on the APMP Boundary Parcel List are within the APMP Boundary. Only those parcels with OWTS that are within the APMP Boundary will be subject to special provisions.
The Interactive APMP Boundary Parcel Map can be used to identify if a specific parcel or property is within the APMP. There is a search bar at the top, right hand corner of the map where you can type your address. The map should zoom you to the identified address. Parcels within the APMP are shaded by a thin transparent layer and highlighted with a yellow boundary.

Local Agencies

County Status Approval Date Approval Resolution Final LAMP
Del Norte Draft      
Humboldt Approved 2/8/2018 Resolution R1-2018-0005 Humboldt County LAMP and Technical Standards Manual
Mendocino Approved 11/4/2018 Resolution R1-2018-0052 Mendocino County LAMP and Technical Standards Manual
Siskiyou Draft      
Sonoma Draft      

  (Page last updated 1/9/23)